1cr 1 2mo

Why are you even contemplating using these materials at that design temperature? The material is in the high temperature Creep regime for design; yield strength is not germane to the design. You truly need to reconsider materials selection.Per Part UHX 13.3 "When a yield strength value is not listed in Table Y-1,one may be obtained by using the procedure in UG-28(c)(2) Step 3" Regards, MikeThanks for your help. Unfortunately, I can't change the material at this stage (budget quote). I tried to suggest alternates, but the customer is not interested at this time.Agree with Standweld, I'm not sure why you're using this material either. Allowable stress around 1,900 at your design temperature? Save yourself and your customer some time and take a look at another material. 347/347H comes to mind. -TJ OrlowskiAgree with Stanweld et al; this is out of the range for 1¼Cr-½Mo.bam-bam.. Another teeny tiny point. A TEMA BEM for 1100+ degrees F ???/? I don't think so. TEMA BEM is good to a maximum of ~ 300F Aside from your client's poor choice of materials, he has a very poor choice of HX design. Ya, ya I know..you are running out of time and you have to bid the spec..your boss is an MBAMJC From your reply it would appear that you have come across the same "numpties" out there with MBA's. It's a pity they have the ultimate say in decision making as they tend to get it wrong on the majority of times.Certainly the wrong material and wrong design. But anyhow, I remember seeing the fixed plate design dwgs for the clinch river liquid sodium HX ( never commissioned), and as I recall, the tubes were twisted, en masse, to allow some flexibility for thermal expansion, shell vs tubes, during transients. Exactly how is your design going to accomodate differential expansion during transients? A beter design would be similar to "header type" heaters, with tubeside fluid distributed / accumulated in internal headers, and the tubes able to move slightly relative to each other , also add thermal sleeves at the header to shell connection. Tubing would be T23 or T91/92, but if T23 tubes are used, the tube stub at the header would need to be another alloy ( non bainitic) if teh heder wall thickness was greater than 1" .I have personally designed a similar unit some years ago, similar metallurgy, similar temperatures, as specified by the customer. Not my preference, certainly, but it can be done. Regards, MikeAfterthought: that WAS before Part UHX was introduced.Author: G. V SmithAuthor: American Petroleum Institute